This paper is devoted to the investigation of crystalline structure, surface morphology, magnetic anisotropy, coercive force and domain structure of spin-valves with a single and double MgO barrier layers. It is shown that domain structure and magnetization reversal are the same for both systems, but otherwise the behavior of tunnel magnetoresistance is different. The approach to control magnetic anisotropy in soft magnetic layer using temperature annealing is demonstrated. It makes these structures possible for new applications in nanoelectronics.